Instruments for measuring forces such as weights are already known which comprise a device for storing the measured weights (for example the successive weights of a person over a certain period of time) and for determining the difference relative to a given weight value (set value or ideal value). However, these known instruments are only capable of indicating values of the numerical difference between the measured value and a reference value, which is inadequate, especially in the case of bathroom scales, because what is useful to the user - and his doctor - is not so much the value of such a difference as the ability to observe and evalute the change in the successively measured values over a certain period of time.
The object of the present invention is to provide an instrument for measuring and recording forces -especially but not exclusively weights - which is capable of showing, in graphical form, the change in the value of the successively measured forces (weights) over a given period of time (for example a week, a month, three months or a year).